[PATCH 1/2] dt-bindings: add simple-audio-mux binding

[PATCH 1/2] dt-bindings: add simple-audio-mux binding

[Alexandre Belloni]

Add devicetree documentation for simple audio multiplexers

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
Cc: Rob Herring <robh+dt@kernel.org>

 .../bindings/sound/simple-audio-mux.yaml      | 41 +++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/sound/simple-audio-mux.yaml

diff --git a/Documentation/devicetree/bindings/sound/simple-audio-mux.yaml b/Documentation/devicetree/bindings/sound/simple-audio-mux.yaml
new file mode 100644
index 000000000000..5986d1fcbb54
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/simple-audio-mux.yaml
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: (GPL-2.0+ OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/simple-audio-mux.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Simple Audio Multiplexer
+
+maintainers:
+  - Alexandre Belloni <aleandre.belloni@bootlin.com>
+
+description: |
+  Simple audio multiplexers are driven using gpios, allowing to select which of
+  their input line is connected to the output line.
+
+properties:
+  compatible:
+    const: simple-audio-mux
+
+  mux-gpios:
+    description: |
+      GPIOs used to select the input line.
+
+  sound-name-prefix:
+    $ref: /schemas/types.yaml#/definitions/string
+    description:
+      Used as prefix for sink/source names of the component. Must be a
+      unique string among multiple instances of the same component.
+
+required:
+  - compatible
+  - mux-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    mux {
+        compatible = "simple-audio-mux";
+        mux-gpios = <&gpio 3 0>;
+    };
-- 
2.28.0

[PATCH 2/2] ASoC: add simple-mux

[Alexandre Belloni]

Add a driver for simple mux driven by gpios. It currently only supports one
gpio, muxing one of two inputs to a single output.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 sound/soc/codecs/Kconfig      |   5 ++
 sound/soc/codecs/Makefile     |   4 ++
 sound/soc/codecs/simple-mux.c | 124 ++++++++++++++++++++++++++++++++++
 3 files changed, 133 insertions(+)
 create mode 100644 sound/soc/codecs/simple-mux.c

diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index 34c6dd04b85a..3847e490f795 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -181,6 +181,7 @@ config SND_SOC_ALL_CODECS
 	imply SND_SOC_SGTL5000
 	imply SND_SOC_SI476X
 	imply SND_SOC_SIMPLE_AMPLIFIER
+	imply SND_SOC_SIMPLE_MUX
 	imply SND_SOC_SIRF_AUDIO_CODEC
 	imply SND_SOC_SPDIF
 	imply SND_SOC_SSM2305
@@ -1240,6 +1241,10 @@ config SND_SOC_SIMPLE_AMPLIFIER
 	tristate "Simple Audio Amplifier"
 	select GPIOLIB
 
+config SND_SOC_SIMPLE_MUX
+	tristate "Simple Audio Mux"
+	select GPIOLIB
+
 config SND_SOC_SIRF_AUDIO_CODEC
 	tristate "SiRF SoC internal audio codec"
 	select REGMAP_MMIO
diff --git a/sound/soc/codecs/Makefile b/sound/soc/codecs/Makefile
index 11ce98c25d6c..90f1a2b7ade0 100644
--- a/sound/soc/codecs/Makefile
+++ b/sound/soc/codecs/Makefile
@@ -305,6 +305,8 @@ snd-soc-tpa6130a2-objs := tpa6130a2.o
 snd-soc-tas2552-objs := tas2552.o
 snd-soc-tas2562-objs := tas2562.o
 snd-soc-tas2764-objs := tas2764.o
+# Mux
+snd-soc-simple-mux-objs := simple-mux.o
 
 obj-$(CONFIG_SND_SOC_88PM860X)	+= snd-soc-88pm860x.o
 obj-$(CONFIG_SND_SOC_AB8500_CODEC)	+= snd-soc-ab8500-codec.o
@@ -613,3 +615,5 @@ obj-$(CONFIG_SND_SOC_MAX9877)	+= snd-soc-max9877.o
 obj-$(CONFIG_SND_SOC_MAX98504)	+= snd-soc-max98504.o
 obj-$(CONFIG_SND_SOC_SIMPLE_AMPLIFIER)	+= snd-soc-simple-amplifier.o
 obj-$(CONFIG_SND_SOC_TPA6130A2)	+= snd-soc-tpa6130a2.o
+# Mux
+obj-$(CONFIG_SND_SOC_SIMPLE_MUX)	+= snd-soc-simple-mux.o
diff --git a/sound/soc/codecs/simple-mux.c b/sound/soc/codecs/simple-mux.c
new file mode 100644
index 000000000000..e0a09dadfa7c
--- /dev/null
+++ b/sound/soc/codecs/simple-mux.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2020 Bootlin SA
+ * Author: Alexandre Belloni <alexandre.belloni@bootlin.com>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <sound/soc.h>
+
+struct simple_mux {
+	struct gpio_desc *gpiod_mux;
+	unsigned int mux;
+};
+
+static const char * const simple_mux_texts[] = {
+	"Input 1", "Input 2"
+};
+
+static SOC_ENUM_SINGLE_EXT_DECL(simple_mux_enum, simple_mux_texts);
+
+static int simple_mux_control_get(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_dapm_context *dapm = snd_soc_dapm_kcontrol_dapm(kcontrol);
+	struct snd_soc_component *c = snd_soc_dapm_to_component(dapm);
+	struct simple_mux *priv = snd_soc_component_get_drvdata(c);
+
+	ucontrol->value.enumerated.item[0] = priv->mux;
+
+	return 0;
+}
+
+static int simple_mux_control_put(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_dapm_context *dapm = snd_soc_dapm_kcontrol_dapm(kcontrol);
+	struct soc_enum *e = (struct soc_enum *)kcontrol->private_value;
+	struct snd_soc_component *c = snd_soc_dapm_to_component(dapm);
+	struct simple_mux *priv = snd_soc_component_get_drvdata(c);
+
+	if (ucontrol->value.enumerated.item[0] > e->items)
+		return -EINVAL;
+
+	if (priv->mux == ucontrol->value.enumerated.item[0])
+		return 0;
+
+	priv->mux = ucontrol->value.enumerated.item[0];
+
+	gpiod_set_value_cansleep(priv->gpiod_mux, priv->mux);
+
+	return snd_soc_dapm_mux_update_power(dapm, kcontrol,
+					     ucontrol->value.enumerated.item[0],
+					     e, NULL);
+}
+
+static const struct snd_kcontrol_new simple_mux_mux =
+	SOC_DAPM_ENUM_EXT("Muxer", simple_mux_enum, simple_mux_control_get, simple_mux_control_put);
+
+static const struct snd_soc_dapm_widget simple_mux_dapm_widgets[] = {
+	SND_SOC_DAPM_INPUT("IN1"),
+	SND_SOC_DAPM_INPUT("IN2"),
+	SND_SOC_DAPM_MUX("MUX", SND_SOC_NOPM, 0, 0, &simple_mux_mux),
+	SND_SOC_DAPM_OUTPUT("OUT"),
+};
+
+static const struct snd_soc_dapm_route simple_mux_dapm_routes[] = {
+	{ "OUT", NULL, "MUX" },
+	{ "MUX", "Input 1", "IN1" },
+	{ "MUX", "Input 2", "IN2" },
+};
+
+static const struct snd_soc_component_driver simple_mux_component_driver = {
+	.dapm_widgets		= simple_mux_dapm_widgets,
+	.num_dapm_widgets	= ARRAY_SIZE(simple_mux_dapm_widgets),
+	.dapm_routes		= simple_mux_dapm_routes,
+	.num_dapm_routes	= ARRAY_SIZE(simple_mux_dapm_routes),
+};
+
+static int simple_mux_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct simple_mux *priv;
+	int err;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, priv);
+
+	priv->gpiod_mux = devm_gpiod_get(dev, "mux", GPIOD_OUT_LOW);
+	if (IS_ERR(priv->gpiod_mux)) {
+		err = PTR_ERR(priv->gpiod_mux);
+		if (err != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get 'mux' gpio: %d", err);
+		return err;
+	}
+
+	return devm_snd_soc_register_component(dev, &simple_mux_component_driver, NULL, 0);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id simple_mux_ids[] = {
+	{ .compatible = "simple-audio-mux", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, simple_mux_ids);
+#endif
+
+static struct platform_driver simple_mux_driver = {
+	.driver = {
+		.name = "simple-mux",
+		.of_match_table = of_match_ptr(simple_mux_ids),
+	},
+	.probe = simple_mux_probe,
+};
+
+module_platform_driver(simple_mux_driver);
+
+MODULE_DESCRIPTION("ASoC Simple Audio Mux driver");
+MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@bootlin.com>");
+MODULE_LICENSE("GPL");
-- 
2.28.0

Re: [PATCH 1/2] dt-bindings: add simple-audio-mux binding

[Mark Brown]

On Sat, 5 Dec 2020 01:15:07 +0100, Alexandre Belloni wrote:
> Add devicetree documentation for simple audio multiplexers

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/2] dt-bindings: add simple-audio-mux binding
      commit: f17a7db22b8ff1688f30bb66aeeaa8cc088e5230
[2/2] ASoC: add simple-mux
      commit: 342fbb7578d1741ff646d7b08e14e8753267b9fa

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

Re: [PATCH 1/2] dt-bindings: add simple-audio-mux binding

[Rob Herring]

On Sat, Dec 05, 2020 at 01:15:07AM +0100, Alexandre Belloni wrote:
> Add devicetree documentation for simple audio multiplexers
> 
> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
> ---
> Cc: Rob Herring <robh+dt@kernel.org>
> 
>  .../bindings/sound/simple-audio-mux.yaml      | 41 +++++++++++++++++++
>  1 file changed, 41 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/sound/simple-audio-mux.yaml
> 
> diff --git a/Documentation/devicetree/bindings/sound/simple-audio-mux.yaml b/Documentation/devicetree/bindings/sound/simple-audio-mux.yaml
> new file mode 100644
> index 000000000000..5986d1fcbb54
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/sound/simple-audio-mux.yaml
> @@ -0,0 +1,41 @@
> +# SPDX-License-Identifier: (GPL-2.0+ OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/sound/simple-audio-mux.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Simple Audio Multiplexer
> +
> +maintainers:
> +  - Alexandre Belloni <aleandre.belloni@bootlin.com>

typo

> +
> +description: |
> +  Simple audio multiplexers are driven using gpios, allowing to select which of
> +  their input line is connected to the output line.

What's wrong with the generic mux binding and driver(s)?

> +
> +properties:
> +  compatible:
> +    const: simple-audio-mux
> +
> +  mux-gpios:
> +    description: |
> +      GPIOs used to select the input line.
> +
> +  sound-name-prefix:
> +    $ref: /schemas/types.yaml#/definitions/string
> +    description:
> +      Used as prefix for sink/source names of the component. Must be a
> +      unique string among multiple instances of the same component.
> +
> +required:
> +  - compatible
> +  - mux-gpios
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    mux {
> +        compatible = "simple-audio-mux";
> +        mux-gpios = <&gpio 3 0>;
> +    };
> -- 
> 2.28.0
> 

Re: [PATCH 1/2] dt-bindings: add simple-audio-mux binding

[Alexandre Belloni]

On 09/12/2020 20:05:45-0600, Rob Herring wrote:
> What's wrong with the generic mux binding and driver(s)?
> 

The main issue is that the driver doesn't expose audio routes and so
DAPM can't do its job properly. Also, it is more convenient to have the
control part of the ALSA sound card which is not possible with gpio-mux.

You could argue that we can have simple-audio-mux use the mux subsystem
but we still need a new binding and driver anyway, just as we have
io-channel-mux or i2c-mux. I'm not sure this would be useful but I can
be convinced otherwise.

> > +
> > +properties:
> > +  compatible:
> > +    const: simple-audio-mux
> > +
> > +  mux-gpios:
> > +    description: |
> > +      GPIOs used to select the input line.
> > +
> > +  sound-name-prefix:
> > +    $ref: /schemas/types.yaml#/definitions/string
> > +    description:
> > +      Used as prefix for sink/source names of the component. Must be a
> > +      unique string among multiple instances of the same component.
> > +
> > +required:
> > +  - compatible
> > +  - mux-gpios
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    mux {
> > +        compatible = "simple-audio-mux";
> > +        mux-gpios = <&gpio 3 0>;
> > +    };
> > -- 
> > 2.28.0
> > 

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com